MULTI-AXIS WATER JET PROPULSION USING COANDA EFFECT VALVES
A propulsion system is provided that includes one or more pumps that form a jet for propulsion. A number of Coanda jet devices (CJDs) are coupled to the one or more pumps. The CJDs are arranged so to allow for a multi-axis underwater control of an underwater robot.
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This application claims priority from provisional application Ser. No. 61/482,272 filed May 4, 2011, which is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTIONThe invention is related to the field of underwater vehicle propulsion and maneuvering, and in particular to a system for propelling and orienting an underwater robot without the use of conventional propeller thrusters.
Since the 1990s, underwater vehicles have become a very popular approach for a number of industrial applications. For example underwater robots have played a major role in the search for undersea wrecks and in the repair of damaged underwater oil risers. Recently there has emerged a new application for such robots: industrial piping systems such as those used for the cooling cycle in nuclear reactor systems. For these applications, the robot must carry a camera or other sensor array and be able to maneuver precisely within the confines of the pipe. For these types of inspections the speed of the robot is actually quite slow. This is to ensure that the robot operator is able to carefully and thoroughly examine the images in real time.
Typical underwater robots use a set of five separate propeller thruster devices. These thrusters are driven by electric motors and have proven quite robust and useful for many applications. However, for certain applications this approach is not desirable. The large number of motors adds considerable mass and volume to the robot. In addition, thrusters exhibit nonlinearities which make them difficult to control when operating at very low speeds or when required to turn on and off rapidly. Finally, reversing the direction of a propeller (something that would be required for fine maneuvers) exerts substantial reaction moments on the body of the vehicle.
SUMMARY OF THE INVENTIONAccording to one aspect of the invention, there is provided a propulsion system. The propulsion system includes one or more pumps that form a jet for propulsion. A number of Coanda jet devices (CJDs) are coupled to the one or more pumps. The CJDs are arranged so to allow for a multi-axis underwater control of an underwater robot.
According to another aspect of the invention, there is provided a method of forming a propulsion system. The method includes providing one or more pumps that form a jet for propulsion. Moreover, the method includes coupling a plurality of CJDs to the one or more pumps. The CJDs are arranged so to allow for a multi-axis underwater control of an underwater robot.
According to another aspect of the invention, there is provided a method of performing the operation of a propulsion system. The method includes forming a jet for propulsion using one or more pumps. Also, the method includes providing multi-axis underwater control using a plurality of CJDs. The CJDs are coupled to the one or more pumps.
The present invention is a jet based approach to multi-axis underwater propulsion and maneuvering, but incorporates a set of custom high speed and compact valves based on well known fluidics technology. Like the previous work on water jet actuation, the underwater vehicle contains an onboard pump and several exit ports. A valve system enables the operator to choose which direction and axis to apply force and moments. Specifically vehicle translation and rotation can be controlled in several axes. Several maneuvering architectures are described herein.
However for the inventive design, a different type of valve is used. A Coanda effect valve based on fluidics technology is used as a valve, allowing the direction of the exit jet to be controlled in a high speed yet compact way.
This invention is unique in several key ways. Most significantly, the invention is specifically designed for multi-axis underwater vehicle control instead of simply switching between two outputs. This architecture uses a number of valves to create forces and moments that can result in translations and rotations along multiple axes. Additionally, the use of a diffuser nozzle to create a null configuration is novel. This allows the pump to remain on while applying zero force or moment to the vehicle. Also, the vehicle to remain stationary momentarily without dealing with the implications of switching the rotary pump on and off repeatedly.
Finally, the specific implementation of the Coanda effect valve is unique. First, the device was designed for use in water alongside a micropump. The geometry of the device therefore differs substantially from the prior art. Additionally, a mechanical design was incorporated that enables the switching of the jet with a single solenoid. This innovation reduces size, weight, and complexity. For the sake of simplicity this entire device is chosen as a CJD. The CJD structure can even be implemented as part of a robot structure itself.
This mode can be controlled without reversing the direction of either pump P1, P2. This means that the while the solenoids can be switching back and forth at a high frequency to achieve precise control, the pumps P1, P2 cannot. This is desirable because a pump like a propeller has undesirable qualities when switched back and forth. To control translational motions in the y direction, the jets 3, 4, C, D can be used. Note that the key difference in this architecture that when the vehicle is in y translation mode the orientation cannot be controlled by the outlets 3, 4, C, D.
The invention provides for multi-axis underwater vehicle control by simply switching between two outputs. The inventive architecture uses a number of valves to create forces and moments that can result in translations and rotations along multiple axes while also allowing for the use of a diffuser nozzle to create a null configuration. This allows a pump to remain on while applying zero force or moment to the vehicle.
Although the present invention has been shown and described with respect to several preferred embodiments thereof, various changes, omissions and additions to the form and detail thereof, may be made therein, without departing from the spirit and scope of the invention.
Claims
1. A propulsion system comprising:
- one or more pumps that form a jet for propulsion; and
- a plurality of Coanda jet devices (CJDs) coupled to the one or more pumps, the CJDs are arranged so to allow for a multi-axis underwater control of an underwater robot.
2. The propulsion system of claim 1, wherein the one or more pumps comprise a plurality of reversible pumps where the CJDs are coupled to each outlet of the reversible pumps.
3. The propulsion system of claim 2, wherein the CJDs allow for translation in a plurality of directions and rotation on one or more axes.
4. The propulsion system of claim 3 further comprising one more diverging nozzles that are positioned on an output of the CJDs.
5. The propulsion system of claim 1, wherein the one or more pumps comprise a plurality of one-way pumps where the CJDs are coupled to each other to form or more tree structures.
6. The propulsion system of claim 5, wherein the tree structures comprise coupling the exits of one of the CJD to at least one exit of the remaining CJDs.
7. The propulsion system of claim 6, wherein the tree structures allow for translation in a plurality of directions and rotation on one or more axes.
8. The propulsion system of claim 7 further comprising one more diverging nozzles that are positioned on an output of the CJDs.
9. A method of forming a propulsion system comprising:
- providing one or more pumps that form a jet for propulsion; and
- coupling a plurality of Coanda jet devices (CJDs) to the one or more pumps, the CJDs are arranged so to allow for a multi-axis underwater control of an underwater robot.
10. The method of claim 9, wherein the one or more pumps comprise a plurality of reversible pumps where the CJDs are coupled to each outlet of the reversible pumps.
11. The propulsion system of claim 10, wherein the CJDs allow for translation in a plurality of directions and rotation on one or more axes.
12. The method of claim 11 further comprising one more diverging nozzles that are positioned on an output of the CJDs.
13. The method of claim 9, wherein the one or more pumps comprise a plurality of one-way pumps where the CJDs are coupled to each other to form one or more tree structures.
14. The method of claim 13, wherein the tree structures comprise coupling the exits of one of the CJD to at least one exit of the remaining CJDs.
15. The method of claim 14, wherein the tree structures allow for translation in a plurality of directions and rotation on one or more axes.
16. The method of claim 15 further comprising one more diverging nozzles that are positioned on an output of the CJDs.
17. A method of performing the operation of a propulsion system comprising:
- forming a jet for propulsion using one or more pumps; and
- providing multi-axis underwater control using a plurality of Coanda jet devices (CJDs), the CJDs are coupled to the one or more pumps.
18. The method of claim 17, wherein the one or more pumps comprise a plurality of reversible pumps where the CJDs are coupled to each outlet of the reversible pumps.
19. The propulsion system of claim 18, wherein the CJDs allow for translation in a plurality of directions and rotation on one or more axes.
20. The method of claim 19 further comprising one more diverging nozzles that are positioned on an output of the CJDs.
21. The method of claim 17, wherein the one or more pumps comprise a plurality of one-way pumps where the CJDs are coupled to each other to form one or more tree structures.
22. The method of claim 21, wherein the tree structures comprise coupling the exits of one of the CJD to at least one exit of the remaining CJDs.
23. The method of claim 22, wherein the tree structures allow for translation in a plurality of directions and rotation on one or more axes.
24. The method of claim 23 further comprising one more diverging nozzles that are positioned on an output of the CJDs.
Type: Application
Filed: Feb 6, 2012
Publication Date: Nov 8, 2012
Patent Grant number: 9205904
Applicant: MASSACHUSETTS INSTITUTE OF TECHNOLOGY (Cambridge, MA)
Inventors: Haruhiko Harry Asada (Lincoln, MA), Anirban Mazumdar (Cambridge, MA)
Application Number: 13/366,659
International Classification: B63H 11/04 (20060101); B23P 15/00 (20060101); B63G 8/08 (20060101);